1. Field of the Invention
The present invention relates to the field of pulling devices, and in particular to a structure of a trigger-boosting pulling device, which comprises a T-shaped pull grip for initial induction of vacuum suction force and a handle comprising a trigger that is operable to supply a force that is subjected to doubling to increase the vacuum suction force.
2. The Related Arts
FIG. 1 shows an exploded view of a hand-operated vacuum pulling device disclosed in U.S. Pat. No. 8,651,458, which is an early invention of the present inventor. The hand-operated vacuum pulling device comprises an elongate shank 70. The elongate shank 70 receives therein a tube 73. The elongate shank 70 receives a backward ram 71 to slidably fit thereto. The elongate shank 70 has a rear end to which a suction cup 72 is mounted. The elongate shank 70 has a front end to which a hand-operating pump holding section 80 that comprises a pressure relief seat 81. The pressure relief seat 81 comprises a relief button assembly 82 and a relief button 83. The pressure relief seat 81 has a bottom forming a ram stop section. The hand-operating pump holding section 80 has a free end to which a ring cover assembly 93 is mounted. The ring cover assembly 93 is made up of a fixed sleeve 931, a ring 932, and a fastening member 933. When a piston assembly 90 is driven to induce vacuum, the ring cover assembly 93 can be then operation to drive the piston assembly 90 to move backward, whereby through being repeated several times, the stiffness of a spring 91 inside the piston assembly 90 is enhanced to increase the vacuum suction force of the suction cup 20 so that, particularly for use with the backward ram, an effect hand-operating pulling effect can be achieved.
Although the early-invented hand-operated vacuum pulling device is effective to supply a vacuum suction force of 550 mbar, it is still insufficient to some extents in practical applications. Further, a pull stem 92 is pressed in a very effort consuming manner to compress the spring 91 arranged therein in order to allow the back springing of the spring 91 to induce vacuum. To obtain a strong vacuum suction force, the spring 91 must be selected and a thick and powerful spring 91 must be used. This, however, requires additional effort to compress the spring 91. The compression is difficult and additional physical strength is needed. This is a drawback to be improved.
Further, in the early-invented hand-operating vacuum pulling device, the backward ram 71 is of a unitary design and such a unitary design would lead to a great waste of material in the manufacturing thereof and the manufacturing is difficult, leading to an increased cost. Improvement is also needed in this respect.
Thus, in view of the drawbacks of the known device, it is desired to provide a solution that overcomes the drawbacks.